Controlled caging and uncaging mechanism

ABSTRACT

A positioning mechanism intended for remote locking and releasing of instruments having a geared down motor driving a cam, the direction and duration of motor rotation being controlled by a circular printed circuit mounted for rotation on the cam shaft, the printed circuit cooperating with a plurality of wiper contacts to effect reversal of polarity in the motor to prevent overtravel thereof.

United States Patent represented by the Administrator of the NationalAeronautics and Space Administration CONTROLLED CAGING AND UNCAGINGMECHANISM Primary Examiner-Lewis H. Myers Assistant ExaminerH. HuberfeldAttorneys-R. F. Kempf, E. Levy and John R. Manning ABSTRACT: Apositioning mechanism intended for remote 2Clalrns,6Drawlng Figs.locking and releasing of instruments having a geared down motor drivinga cam, the direction and duration of motor rotac 12 4/ 3 tion beingcontrolled by a circular printed circuit mounted for I CI rotation onthe cam shaft, the printed circuit cooperating with ui g 26 a pluralityofwiper contacts to effect reversal of polarity in the o motor toprevent overtravel thereof.

IIII I 1 I I II I2 L I 24" w 2 i E I I BA I I 32 I6 I 33 I 9 IILI I I lI I Patented Dec. 14, 1971 2 Sheets-Sheet 2 ML ED w WT S M W Du BY 4MLiz/J ATTORNEYS used by-or for the United States Government forGovernmental purposes without the payment of any royalties thereon ortherefor.

BACKGROUND OF THE INVENTION This invention relates to a mechanism forautomatically locking and unlocking instruments where the actuatedmechanism weight is small in relation to the locking force required.

In the past, systems have been designed to actuate and/or shut downmechanisms in response to a signal from a remote point such asinstruments used in lunar landings. These systems have taken the form ofbulky mechanical arrangements coupled with the necessary electricalcircuitry to actuate them or a pneumatic device using an explosiveactuator arrangement which utilizes the force of a small explosion tolock or unlock the instrument.

The disadvantages of such prior systems are numerous. They are incapableof being cycled automatically and require replacement of parts. Theexplosive-type system has the inherent drawback of transmitting asignificant amount of shock to the device being actuated. If a gas isused to impart an explosive-type force, the system may experience gasleakage. Also, the explosive actuator has to be placed at some distancefrom the instrument to minimize the shock.

The electromechanical systems do not meet the weight or capabilityrequirements needed under the general parameters of this invention.

It is these past problems, especially in activation and deactivation ofinstruments used in lunar landings that led to the development of thepresent invention.

GENERAL DESCRIPTION This invention utilizes a motor to drive a cam andgear mechanism, which cam actuates a plunger or other directional forcetransmitting means to lock or unlock an instrument. A disc having aprinted circuit thereon is utilized in conjunction with a plurality ofbiased contacts to automatically stop the motor in predetermined lockand unlock positions in regard to plunger disposition. A switch, whichcan be actuated by suita ble electronics upon receiving a remote signal,activates the motor which is preferably geared down. A worm gear andworm wheel are usedto transmit motor rotation to rotation of a shaftcarrying the cam and printed circuit disc. The design of the printedcircuit is such that the motor circuit is broken when the plungerreaches a predetermined position. The design of the disc printed circuitalso sets up the circuit for motor reversal upon reactivation oftheswitch.

The invention can be applied to lock and unlock, position, or drive,with controlled velocity. items in hazardous environments where space orweight are extremely limited.

OBJECTS OF THE INVENTION Accordingly it is an object of this inventionto provide an automatic locking and unlocking device.

A further object of this invention is to provide an automatic lockingand unlocking mechanism that can be cycled continuously.

A still further object of this invention is to provide an automaticpositioning mechanism that can be tested without necessitatingreplacement of any parts.

A further object of this invention is to provide an automaticpositioning mechanism having a shock-free operation and readilyadjustable in the test area.

A further object of this invention is to provide an automaticpositioning mechanism which includes a motor driving a disc which has aprinted circuit thereon engaging biased contact arms and adapted toautomatically stop rotation of the motor and set up the circuitry forreversal of the motor.

These and other objects will become apparent during the followingdescription taken with reference to the drawings in which:

FIG. 1 is a front view of the positioning mechanism showing itfunctioning with a lunar seismometer.

FIG. 2 is a plan view of the device shown in FIG. 1 with the seismometerapparatus removed.

FIG. 3 is a front view of the position mechanism in a slightly difierentseismometer housing and showing the biased contact arms.

FIG. 4 is a partial side view of the mechanism of FIG. 3 showing themotor and worm gear arrangement.

FIG. 5 is a partial perspective of the positioning mechanism showing theprinted circuit disc and the relationship between the printed circuitand the biased contact arms.

FIG. 6 is an electrical circuit diagram of the positioning mechanism.

Referring now to FIG. I, there is shown a seismometer cage 2 consistingof base plate 4, a guide plate 6 and a top plate 8. Plate 4, as shown inFIG. 2, is generally the shape of an equilateral triangle with agenerally square portion 5 extending therefrom.

Securing top plate 8 to guide plate 6 are elongated spacers l0, 12 whichare internally threaded at one end to receive threaded studs such as 18which are mounted in guide plate 6. Screws 20 lock the top plate to theelongated spacers 10, I2. Securing guide plate 6 and base plate 4 areconnected together in the same manner by short spacers 14, 16; it beingunderstood that there is another elongated spacer and short spacer notvisible in FIG. 1.

Positioned within the cage, provided by the elongated spacers, is aseismometer mass 22 which is suspended by a wire 23 to a mass suspensionarm (not shown). The numerous details of the seismometer are not shownsince the seismometer forms no part of this invention. The cage and massof the seismometer are only shown to demonstrate the relationship ofoneinstrument to the positioning mechanism.

The base of mass 22 is countersunk as at 24 to receive the tapered endofa plunger 26 which is mounted for vertical sliding movement in guideplate 6.

On base plate 4, there are secured two shaft mounting brackets 28 and30, each bored to receive shaft 32. Mounted on shaft 32 intermediate thebrackets is a cam 34 held in position on the shaft, below and in contactwith plunger 26, by a setscrew 31 passing through an annular section 35of the cam as shown in FIG. 2. A locking member 33 is secured to one endof the shaft and is held there by a screw similar to 31. A nonconductivedisc 36 is mounted on the shaft by a set screw passing through anannular section 37 thereof. A printed circuit 39 is provided on the endface of disc 36. The disc 36 and locking member 33 preclude longitudinalmovement of shaft 32.

A gear 38 is mounted on shaft 32 and is positioned to engage a worm 40mounted'on the shaft 42 of a motor 44.

Motor 44, as seen in FIGS. 3 and 4, is held within a circular bracket 46having extension ears 48 and 50. Base plate 4 has a mounting flange 53,and the extension ears of the bracket 46 are mounted thereto by a pairof screws 52 and nuts 54.

Also mounted on base plate 4, by any suitable means (not shown), is anonconductive plate 45. As seen in FIGS. 3 and 5, a series of biasedcontact arms FIG. 62, 64 and 66 are mounted thereto and are adapted toresiliently engage the printed circuit 39 on disc 36. The configurationof the arms may be as shown in FIG. 5 where, in the case of arm 60, ithas a portion 61 bent at right angles to the portion secured to theplate 45 and a further portion 63 bent atapproximately right angles toportion 61. A more preferred form is illustrated in FIG. 2 in the caseof arm 60', where the portion 63' is offset from portion 61' byapproximately 45 and has a lip 65'. The juncture of lip 65' and portion63' engage the printed circuit 39.

Referring now to FIGS. 5 and 6, the printed circuit 39 on disc 36 isseen to have an outer closed loop which connects with an inner open loop72 by radial portion 71. Loops 70 and 72 and portion 71 constitute onecircuit designated as X. Positioned between loops 70 and 72 is an openloop 74 which connects with a smaller inner closed loop 76 through aradial portion 75. Loops 74 and 76 and portion 75 constitute a secondcircuit designated as Y. As shown in FIG. 6, contact 60 engages loop 70,contact 62 engages loop 74, contact 64 engages loop 72 and contact 66engages loop 76. Le, contacts 60 and 64 engage circuit X and contacts 62and 66 engage circuit Y.

Contacts 60 and 66 are connected to battery sources 82 and 84,respectively; they are also connected to opposite poles of thebatteries.

The opposite poles of the batteries are connected to motor 44 which, inturn, is connected with a switch 80, a double throw type of switch.Contacts 62 and 64 are connected to the switch 80.

OPERATION OF THE MECHANISM When the switch 80 is moved, by any suitablemeans, such as by hand or by a relay (not shown) energized by a remotesignal. to an up position, as viewed in FIG. 6 by a dash line, theelectrical circuit is completed in circuit X through loops 70 and 72 andradial portion 71. This energizes motor 44 which turns shaft 32 torotate cam 34. If the plunger 26 is already in a locking position,rotation of cam 34 releases plunger 26 and unlocks mass 22. The plunger29 may be spring biased downwardly if desired. When the gap 90, betweenthe end of loop 72 and radial portion 75, reaches contact 64, thecircuit X is broken and the motor is stopped. if the shaft 32overtravels, the wiper contact 64 on loop 74 touches the radial portion75 (assuming clockwise rotation as viewed in FIG. 6) between loops 74and 76, thus reversing the polarity to the motor. This reversing actionnegates the motor overtravel and stops the movement with wiper contact64 in the gap 90 between the end of loop 72 and radial portion 75.

Reverse movement, to lock or unlock, depending upon the originalcondition is accomplished by moving the single pole double throw switch80 to the down position to energize circuit Y to drive the motor 44counterclockwise. When the gap 92, between the end of loop 74 and radialportion 71, reaches wiper contact 62, the circuit Y is opened, thuslocking the plunger in place. Overtravel of the shaft 32 is prevented bypolarity reversal when the contact 62 contacts radial portion 71bridging loops 70 and 72.

The cam 34 may be adjusted to any suitable position by looseningsetscrew 31 and manually rotating the cam on shaft 32.

It is seen that overtravel is prevented by the reversal of polaritythereby reversing the direction of rotation of the motor to effect anopen circuit. The position of the disc is set up for a counter rotationthe original direction of rotation, by repositioning the movable contactarm of switch 80.

The motor is preferably a DC motor which is internally geared down from16,700 rpm. to 283 rpm. to provide 5.5 ounce-inches of torque. Theexternal worm gear reduction is on the order of 37: I.

it is apparent that the positioning mechanism has many otherapplications besides that of locking and unlocking a seismometer. It canbe used to position other instruments where a highly reliable mechanismis desired when the requirements are that the system weight must besmall with respect to the locking force involved. In the embodimentshown, the entire system weighs only 57 grams including a 23 gram motorand it provides over 200 pounds of locking force along the plunger axis.

The mechanism thus can be used in many other applications, too numerousto mention, where the requirements are such that conventional systemsare too heavy or impart a shock to the device being positioned orlocked. it is further apparent that many changes and modifications willbe obvious to one skilled in the art without departing from the scope ofthe appended claims.

What is claimed is: 1. A mechanism for caging and uncaging an instrumentcomprising;

motor means;

motion translating means having a shaft with a cam attached thereto;

gear reduction means coupling said motor means to said shaft of saidmotion translating means;

plunger means operated by said cam to cooperate with said instrument toachieve caging and uncaging thereof; power source means;

planar circuit means operatively connected to said shaft of said motiontranslating means and adapted to rotate therewith, said planar circuitmeans comprising a disc having a printed circuit pattern on one facethereof formed of four concentric conductive loops including an outerclosed loop, an inner closed loop and two middle loops located betweenthe outer closed loop and the inner closed loop, said outer closed loopbeing connected to the innermost one of said two middle loops by a firstradial conductive portion, said inner closed loop being connected to theoutermost one of said two middle loops by a second radial conductiveportion, the printed circuit pattern providing gaps in the outermost oneof said middle loops and the innermost one of said middle loops;

four wiper contacts, each riding on a respective one of said fourconcentric conductive loops;

switch means;

second circuit means connecting said motor means, said power sourcemeans, said switch means and said four wiper contacts to form, inconjunction with said printed circuit pattern, two sub-circuits adaptedto control the rotation of said motor means in opposite directions andto reverse the polarity of said motor means at a predetermined point inits rotation, in either direction, in accordance with the location ofsaid gaps, the middle two wiper contacts of said four wiper contactsadapted to respectively engage said gaps to open the respectivesubcircuit to stop said motor means and to reverse polarity of saidmotor means if overtravel occurs, thereby permitting said cam toposition said plunger to precisely cage and uncage said instrument.

2. A mechanism as in wiper 1 wherein said reduction gear means comprisesa worm driven by said motor means and engaging gear means on said shaft;said power source means comprises two batteries; said switch means is asingle pole double throw switch; and said second circuit means connectsopposite poles of said batteries to said motor means and said motormeans to the single pole of said switch, the other opposite poles ofsaid batteries being connected respectively to said wiper contactsriding on the outer closed loop and the inner closed loop, the middletwo of said four wiper contacts being connected to said switch, wherebyactuation of said switch effects clockwise or counterclockwise rotationof said motor means depending upon the direction of throw of saidswitch.

1. A mechanism for caging and uncaging an instrument comprising; motormeans; motion translating means having a shaft with a cam attachedthereto; gear reduction means coupling said motor means to said shaft ofsaid motion translating means; plunger means operated by said cam tocooperate with said instrument to achieve caging and uncaging thereof;power source means; planar circuit means operatively connected to saidshaft of said motion translating means and adapted to rotate therewith,said planar circuit means comprising a disc having a printed circuitpattern on one face thereof formed of four concentric conductive loopsincluding an outer closed loop, an inner closed loop and two middleloops located between the outer closed loop and the inner closed loop,said outer closed loop being connected to the innermost one of said twomiddle loops by a first radial conductive portion, said inner closedloop being connected to the outermost one of said two middle loops by asecond radial conductive portion, the printed circuit pattern providinggaps in the outermost one of said middle loops and the innermost one ofsaid middle loops; four wiper contacts, each riding on a respective oneof said four concentric conductive loops; switch means; second circuitmeans connecting said motor means, said power source means, said switchmeans and said four wiper contacts to form, in conjunction with saidprinted circuit pattern, two sub-circuits adapted to control therotation of said motor means in opposite directions and to reverse thepolarity of said motor means at a predetermined point in its rotation,in either direction, in accordance with the location of said gaps, themiddle two wiper contacts of said four wiper contacts adapted torespectively engage said gaps to open the respective sub-circuit to stopsaid motor means and to reverse polarity of said motor means ifovertravel occurs, thereby permitting said cam to position said plungerto precisely cage and uncage said instrument.
 2. A mechanism as in claim1 wherein said reduction gear means comprises a worm driven by saidmotor means and engaging gear means on said shaft; said power sourcemeans comprises two batteries; said switch means is a single pole doublethrow switch; and said second circuit means connects opposite poles ofsaid batteries to said motor means and said motor means to the singlepole of said switch, the other opposite poles of said batteries beingconnected respectively to said wiper contacts riding on the outer closedloop and the inner closed loop, the middle two of said four wipercontacts being connected to said switch, whereby actuation of saidswitch effects clockwise or counterclockwise rotation of said motormeans depending upon the direction of throw of said switch.